Novel Casein-Surfactant-Micelles as Carrier for Nutraceuticals

The aim of this Ph.D. project is to develop a new type of self-assembled carrier systems, composed of caseins and surfactants for encapsulation of hydrophobic bioactive compounds. Caseins are major constituents of milk. These proteins typically precipitate out of milk if the pH is decreased below 4,6. Caseins act like surfactants, their emulsification properties have been well studied and used in a large variety of applications. In the literature it has been proposed, that caseins have a structure similar to that of block copolymers. Block copolymers consist of blocks of different polymerized monomers and are typically produced synthetically. Molecular modeling has shown that α_s1-casein has a triblock copolymer structure of  two hydrophobic blocks at the N- and C-terminal end and one hydrophilic group in between, α_s2-casein is a tetrablock copolymer with alternating hydrophobic and hydrophilic blocks starting from the N-terminal end,  β-casein is a diblock copolymer with a hydrophilic bock at the N-terminal and a hydrophobic block at the C-terminal;  while finally κ-casein is a diblock copolymer and a mirror of  β-casein.

The objective of this work is to establish the conditions required to form mixed micelles from casein and synthetic surfactants. These thermodynamically-stable aggregates are formed when amphiphilic materials are dissolved in a solvent at concentrations that exceed the so-called critical micelle concentration (cmc). Depending on the surfactant concentration, the temperature, the pH, and the ionic strength, non-spherical micellar aggregates, bilayers and vesicles may be formed instead of regular micelles.

In subsequent step, a hydrophobic material will be encapsulated in the carrier system. The encapsulation should be “smart”  and allow for the encapsulated material to be released only in the gastrointestinal tract. As an example for a hydrophobic material, Vitamin D₂ has been chosen. A second material, less hydrophobic with a substantially higher partitioning coefficient in water, we propose to use eugenol, a phytophenol with antimicrobial and antioxidant activities. The aim is to attain a sufficiently high stability of the encapsulated compounds and to correlate the functionality of the system to the properties of the carrier (e.g. interfacial composition, size, charge).

In a third workpackage, the encapsulated compounds are to be included in foods. Here, the technological properties of the capsule-containing foods will be investigated (i.e ability to survive a range of processing steps that are characteristics to the processing of many foods in the food industry).

This project is conducted in collaboration with the Department of Animal Foodstuff Technology. The combination of expertise in nanoscience and dairy sciences is essential to the success of the project. The project originates from the joint interest of the two advisors on the project, Profs. Dr. J. Hinrichs and J. Weiss to develop new functional foods with health and wellness promoting properties.